Illumos 2077 - lots of unreachable breaks in illumos gate

Illumos 2077 - lots of unreachable breaks in illumos gate

2077 lots of unreachable breaks in illumos gate
Reviewed by: Dan McDonald <danmcd@nexenta.com>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/2077
  https://github.com/illumos/illumos-gate/commit/33f5ff1

Porting notes:
- Only one file of the original patch applied to ZFS
- Minor formating change to align copyright block with upstream

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>